1. Field of the Invention
The present invention relates to a regulator serving as one of air conditioning units in a pneumatic system, and, more particularly, to a technique applied to a structure for connecting a regulator with other air conditioning units. The term "air conditioning unit" is used here in a broad sense including not only a regulator, a filter, a lubricator, etc., but also a pipe coupling.
2. Related Art Statement
As a regulator or the structure for connection of other air conditioning units to the regulator in a pneumatic system, the following arrangement is considered, for example:
Specifically, in the case where a single unit of the regulator is connected to pipes, the structure for connection of the air conditioning unit is arranged such that a pipe on the upstream side is connected to an inflow port of a regulator body by means of threaded engagement, and a pipe on the down stream side is connected to an outflow port of the regulator body by means of threaded engagement.
Further, in the case where a filter is connected to the regulator, a structure for connection of the air conditioning units is arranged such that the filter is connected to the inflow port of the regulator body through a nipple, and a pipe is connected to the outflow port of the regulator body by threaded engagement.
Furthermore, in the case where the filter and a lubricator are connected to the regulator, a structure for connection of the air conditioning units is arranged such that the filter is connected to the inflow port of the regulator body through the nipple, and the lubricator is connected to the outflow port of the regulator body through a nipple.
However, the structure for connection of the air conditioning units in the case where the regulator is used by itself has the following problem. That is, since the pipe on the upstream side and the pipe on the downstream side are connected respectively to the inflow port and the outflow port of the regulator body by means of threaded engagement, connection of pipes different from the regulator in diameter of inflow and outflow ports is impossible so that it is difficult to select the pipe diameter.
Furthermore, the structure for connection of the air conditioning units in the case where the filter is connected to the regulator has the following problem. That is, the filter is connected to the inflow port of the regulator through the nipple, and the pipe is connected to the outflow port of the regulator body. Thus, not only the entire length increases, but also selection of the pipe diameter is made difficult.
Moreover, there is the following problem. That is, if the filter and the lubricator are connected to the regulator such that the filter and the lubricator are directed or oriented in the same direction as the regulator, loosening of the nipples generates leakage of air.
The structure for connection of the air conditioning units in the case where the filter and the lubricator are connected to the regulator has the following problem. That is, the arrangement is such that the filter and the lubricator are connected respectively to the inflow and outflow ports of the regulator body through the nipples. Thus, the entire length further increases, and the number of parts also increases. Further, mounting or attaching is troublesome and cumbersome.
Furthermore, there is the following problem. That is, if the filter and the lubricator are connected to the regulator such that the filter and the lubricator are directed in the same direction as the regulator, loosening of the nipples will cause air leakage.
Moreover, it is desired to mount a pressure gage on the regulator in order to detect pressure within the regulator body of the regulator.
An example of the structure for mounting the pressure gage on the regulator is disclosed, for example, in Japanese Utility Model Laid-Open No. 62-121494.
Specifically, the structure for mounting the pressure gage to the regulator is arranged such that the pressure gage is mounted to the outer peripheral surface of the regulator body, and the periphery of the regulator body is covered with a cover made of synthetic resin under such a condition that the pressure gage projects.
However, the aforesaid structure for mounting the pressure gage to the regulator has the following problem. That is, at mounting of the pressure gage, the pressure gage is mounted to the outer peripheral surface of the regulator body, and the periphery of the regulator body is covered with the cover under the condition that the pressure gage projects. Further, at demounting of the pressure gage, it is necessary that the cover is removed and, subsequently, the pressure gage is removed from the regulator body. Thus, mounting and demounting of the pressure gage are troublesome and cumbersome.
Further, the structure for mounting the pressure gage on the regulator has the following problem. That is, the pressure gage is mounted to the outer peripheral surface of the regulator body, and the periphery of the regulator body is covered with the cover under the condition that the pressure gage projects. Accordingly, not only the regulator increases in size correspondingly to the cover, but also the regulator is made to look less attractive with respect to the external appearance.
Further, it is desired to display, in a viewable manner, detected pressure of the pressure gage to confirm the detected pressure from the outside.
As the regulator of the kind referred to above having the pressure display function, there is the following one. That is, a pressure gage of Bourdon-tube type, which communicates with a secondary passage of the regulator, that is, with a passage thereof on the outflow side, to detect secondary pressure, is mounted on the regulator body by means of threaded engagement. The secondary pressure is detected and can be displayed by an indicating needle.
For the structure of the regulator having the pressure display unit, however, various problems have been pointed out in the present when reduction in size of a regulator and integration thereof have advanced.
For example, in the case where the regulator is to be reduced in size, there is the following disadvantage or defect. That is, there is a limit in reduction in size of the pressure gage of Bourdon-tube type, and accuracy in measurement is extremely deteriorated.
In this case, the following problems arise. That is, it is particularly impossible to directly mount the pressure gage on a regulator of manifold-type. The pressure gage must be mounted at a different place to practice detection through the pipes.
Furthermore, there are the following problems. That is, the function of the pressure gage of the above-described type is only pressure display, and the pressure gage does not have a pressure-detection function and an abnormality detection function attendant thereupon. In the case, for example, where the secondary pressure abnormally deviates from the setting pressure, it is impossible to cope with the abnormality.
Moreover, the above-described structure has the following problem. That is, it is difficult to respond with respect to repeated pressure fluctuation, and breakage occurs in a driving system for the needle and the like.
Accordingly, there are the following problems. That is, the conventional pressure gage of Bourdon-tube type has the above-discussed problems not only in the functional aspect, but also in the structural aspect. Further, it is difficult to cope with reduction in size of the pneumatic-pressure instruments of the present day and integration thereof.